U.S. Pat. No. 4,521,772, which issued on June 4, 1985, discloses a cursor control device, or "optical mouse" for use with an interactive display oriented computer system to provide movement for a visible cursor from position to position on a display screen of such a system. The device include an IC (intetrated circuit) chip that contains on optical sensor array and circuitry to bring about detectable bit maps based upon a plurality of sensor cells making up the array. the distinguishable bit maps are employed as a means for comparison to provide an output indicative of the direction and amount of movement of the cursor control device relative to an optical contrasting input to the array, the output being employed as a means to move the visible cursor from position to position on a display screen.
U.S. Pat. No. 4,521,773, also issued on June 4, 1985, and assigned to the same assignee as the previous patent and the present application, discloses an imaging array which provides a plurality of distinguishable bit map images and comprises an array of sensor cells capable of sensing radiation. The cells are connected in a manner to form distinguishable bit map images through a pattern of correspondence among the cells. Each bit map image formed comprises a combination of one or more cells indicative of detecting an image pixel within a field of array cells that have been non-indicative of such detection. The pattern of correspondence may be one of inhibition of the operation of other cells in the array or one of indication of operation to other cells in the array. Various patterns of correspondence can be created among the cells creative of bit map images. Bit map images may consist of combinations of responsive cells within a field of nonresponsive cells in the array. For example, each bit map image may comprise radiation responsive array cells that have sensed a sufficient quantity of radiation within a field of cells which have not sensed radiation or have been inhibited from sensing radiation. On the other hand, each bit map image may comprise cells that have not sensed a sufficient quantity of radiation within a field of cells that have sensed a sufficient quantity of radiation. An application of the imaging array is in an IC chip for a cursor control device or an "optical mouse" for use with an interactive display oriented computer system to provide movement for a visible cursor from position to position on a display screen of such a system.
The optical mouse as disclosed in these two patents were operative as disclosed but found to have a difficulty in the focus alignment for the light reflected from the illuminated pattern pad to the optical sensor array on the integrated circuit chip. Improvement was necessary and work was undertaken to create an optical mouse which did not include the folded optics as disclosed in the two patents set forth above.
According to the present invention, an optical mouse is disclosed wherein light emanating from the light source is reflected off an optical pattern pad and is placed such that a lens at a predetermined distance from the optical pad focuses the light directly onto an inverted integrated circuit mounted on and through a hole in a printed wiring board, said integrated circuit being housed in a clear plastic package. The path from the lens to the integrated circuit package provides an optical guide such that the distances from the pattern pad to the lens, and from the lens to the optical sensor in the integrated circuit, is fixed upon manufacture and assembly without any further optical adjustment. The inverted state of the integrated circuit chip allows a fixed distance to be provided through the hole in the printed wiring board rather than from above it as is common in the prior art.